Jakob-
Ah - that?s the fault! The link [[Category:Stuff]] should refer to the article "Stuff" and not to some special-category-only article. [[Category:Biology]] *is* [[Biology]]! Please have a look at the actual article [[en:Biology]]: What does ==Fields of study in biology== contain but a listing of subtopics? Why introduce a new artificial namespace when you can better name the article for instance "Fields of study in biology"?
Because this will standardize these lists and automate them at the same time. Currently we have "List of xy topics", with lots of Wikipedia- related meta information, floating around in the regular namespace. These are not really articles and they should not be counted as such. Having [[Category:Mathematics]], [[Category:Biology]] etc. is much more economic and only shows the information to those who care about it.
Possible problem: Does "Related changes" still work on category pages? We might need to modify that.
Regards,
Erik